检索结果-南通市图书馆

crustal structure study based on principal component analysis of receiver functions

Science China Earth Sciences 2019年第7期62卷 1110-1124页

作者： Jianyong ZHANG Ling CHEN Xu WANG State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences

The receiver function(RF) technique is an effective method for studying crustal structure. For a single station, the average 1-D crustal structure is usually derived by stacking the radial RFs from all back-azimuths, whereas structural variations(such as dipping discontinuities or anisotropy) can be constrained through analysis of waveform dependence on the backazimuth of both the radial and tangential RFs. However, it is often difficult to directly extract information about structural variations from the waveform of RF, due to the common presence of noise in real data. In this study, we proposed a new method to derive structural variation information for individual stations by applying principal component analysis(PCA) to RFs sorted by back-azimuth. In this method(termed as RF-PCA), a set of principal components(PCs), which are uncorrelated with each other and reflect different characteristics of the RF data, were extracted and utilized separately to reconstruct new RFs. Synthetic tests show that the first PC of the radial RFs contains the average structural information of the crust beneath the corresponding station, and the second PC of the radial RFs and the first PC of the tangential RFs both reflect the variations of the crustal structure. Our synthetic modeling results indicate that the new RF-PCA method is valid for a variety of synthetic models with intra-crustal dipping discontinuities and/or anisotropy. We applied this method to the real data from a broadband temporary seismic station(s233) in the central part of the Sichuan Basin. The results suggest that the RF data can be best explained by the presence of two nearly parallel dipping discontinuities within the crust. Combining with previous logging data, seismic exploration and deep sounding observations, we interpret the shallow dipping discontinuity as the top boundary of the Precambrian crystalline basement of the Sichuan Basin and the deep one corresponding to the Conrad interface between the upper a

关键词： Principal component analysis Receiver function crustal structure Dipping discontinuity Anisotropy Sichuan Basin

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

crustal reworking and orogenic styles inferred from zircon Hf isotopes:Proterozoic examples from the North Atlantic region

引用

Geoscience Frontiers 2019年第2期10卷 417-424页

作者： C.J.Spencer C.L.Kirkland A.R.Prave R.A.Strachan V.Pease Earth Dynamics Research Group The Institute of Geoscience Research (TIGeR)Department of Applied GeologyCurtin University Centre for Exploration Targeting d Curtin Node Department of Applied GeologyCurtin University Department of Earth and Environmental Sciences University of St Andrews School of Earth and Environmental Sciences University of Portsmouth Department of Geological Sciences Stockholm University

Zircon Hf evolutionary patterns are powerful tools to investiage magma petrogenesis and crustal evolution. The ^(176)Hf/^(177)Hf isotopic signature of a rock is particularly informative and can be used to derive an estimation of the time when mantle extraction and diagnose closed system reworking where successive samples through time define an Hf evolution array dependant on the source Lu/Hf ratio. However, many magmatic events require new mantle addition as the thermal impetus for melting pre-existing crust. In this situation, rather than simply reflecting reworking, the isotopic signature indicates mixing with contributions from both reworked crust and new radiogenic input. Different geodynamic settings have different propensities for either reworking or addition of new mantle-derived magma. Hence, Hf-time trends carry within them a record, albeit cryptic, of the evolving geodynamic environment as different tectonic configurations recycle and add new crust at different rates, magnitudes, and from different sources. As an example of the difference in apparent Hf evolution slopes, we present Hf-time compilations from three geographically distinct Meso-to Neoproterozoic orogenic belts in the North Atlantic Region whose geodynamic configurations remain a subject of debate. We use the εHf/Ma trajectory to assist in understanding their evolution. The εHf/Ma trajectory of the Sveconorwegian Orogen corresponds to a ^(176)Lu/^(177) Hf ratio of 0.012, which implies a process driven primarily by reworking of preexisting crust that is balanced with input from the depleted mantle resulting in a relatively shallowεHf/Ma slope. The Valhalla Orogen reveals a similar comparatively shallow εHf/Ma path. In stark contrast to these patterns is the steep εHf/Ma trajectory of the Grenville Orogen that requires a mixing process involving a greater contribution of old crust of at least ～ 1.8 Ga age. The degree of reworking required to produce the εHf/Ma trend of the Grenville Orogen is co

关键词： Zircon Hf crustal evolution Grenville Sveconorwegian Valhalla

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

High-resolution 3D crustal S-wave velocity structure of the MiddleLower Yangtze River Metallogenic Belt and implications for its deep geodynamic setting

引用

Science China Earth Sciences 2019年第9期62卷 1361-1378页

作者： Song LUO Huajian YAO Qiusheng LI Weitao WANG Kesong WAN Yafeng MENG Bin LIU Laboratory of Seismology and Physics of the Earth’s Interior School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China National Geophysical Observatory at Mengcheng University of Science and Technology of China Mengcheng 233500 China Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China Institute of Geophysics Chinese Earthquake Administration Beijing 100081 China

The Middle-Lower Yangtze River Metallogenic Belt(MLYMB) is an important mineral resource region in ***-resolution crustal models can provide crucial constraints to understand the ore-forming processes and geodynamic setting in this region. Using ambient seismic noise from 107 permanent and 82 portable stations in the MLYMB and the adjacent area,we present a new high-resolution 3D S-wave velocity model of this region. We first extract 5–50 s Rayleigh wave phase velocity dispersion data by calculating ambient noise cross-correlation functions(CFs) and then use the surface wave direct inversion method to invert the mixed path travel times for the 3D S-wave velocity structure. Checkerboard tests show that the horizontal resolution of the 3D S-wave velocity model is approximately 0.5°–1.0° and that the vertical resolution decreases with increasing noise and depth. Our high-resolution 3D S-wave velocity model reveals:(1) AV-shaped high-velocity zone(HVZ) is located in the lower crust and the uppermost mantle in the study region. The western branch of the HVZ passes through the Jianghan Basin,the Qinling-Dabie orogenic belt and the Nanxiang Basin. The eastern branch, which almost completely covers the main body of the MLYMB, is located near the Tanlu Fault. The low-velocity anomalies between the western and eastern branches are located in the area of the Qinling-Dabie orogenic belt.(2) High-velocity uplifts(HVUs) are common in the crust of the MLYMB,especially in the areas near the Tanlu Fault, the Changjiang Fault and the Yangxin-Changzhou Fault. The intensities of the HVUs gradually weaken from west to east. The V-shaped HVZ in the lower crust and uppermost mantle and the HVUs in the middle and lower crust likely represent cooled mantle intrusive rocks. During the Yanshanian period, fault systems formed in the MLYMB due to the convergence between the South China Plate and the North China Plate, the multiple-direction drifting of the PaleoPacific Plate and its subd

关键词： Middle-Lower Yangtze River Metallogenic Belt Ambient noise Surface wave crustal structure Mineralization dynamics

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

crustal Heat Production and Mantle Heat Flow in Southeast China

引用

Science China Chemistry 1994年第10期37卷 1252-1263页

作者：胡圣标汪集旸 Institute of Geology Academia SinicaBeijing 100029PRC

The correlation between seismic velocity (v_p) and radiogenic heat production (A) en- ables the distribution of crustal heat production to be evaluated,from which the mantle heat flow for 21 seismic velocity-depth profiles located along the two continental geotraverses in Southeast China can be *** approaches have been proposed to special problems connected with the conversion of seismic velocities into heat production in orogenic *** results show that the crustal heat flow in Southeast China is quite inhomogeneous,varying between 17.8 and 46 mW·m^(-2),which can be attribut- ed to the complicated crustal structure related to overthrusting and overlapping in the upper *** re- markable regional variation in the mantle heat flow,ranging from 23.2 to 41.6 mW·m^(-2),corresponds to the large-scale tectonothermal evolution of the orogenic belts.

关键词： v_p-A conversion crustal heat production mantle heat flow Southeast China

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

crustal Deformation Revealed by GPS in Kumaun Himalaya,India

引用

Journal of Mountain Science 2014年第1期11卷 41-50页

作者： Rakesh K.DUMKA Bahadur S.KOTLIA Kireet KUMAR Gokul S.SATYAL Lalit M.JOSHI Institute of Seismological Research Centre of Advanced Study in Geology Kumaun University G.B.Pant Institute of Himalayan Environment and Development

The foremost Global Positioning System(GPS) derived measurements in the Kumaun Himalaya indicate that most of the crustal motion of the Indian plate is accommodating towards the base as well as on the hanging wall of Main Central Thrust(MCT).Deformation pattern within the Kumaun Himalaya varies from south to north and indicates maximum deformation rate near *** study,based on the campaign mode GPS survey during 2003- 2006,reveals that the area between north of North Almora Thrust(NAT) and at the base of Great Himalaya registers maximum strain rate,which is lowered towards the Trans Himadri Fault(THF).The GAMIT-GLOBK processed campaign data of the area show that currently,the Himalayan Frontal Fault(HFF) and Main Boundary Thrust(MBT) are locked with the Indian plate,and a 6.7 ± 2.5 mm/yr of horizontal shortening is taking place between the Lesser Himalaya and Peninsular India.

关键词： Kumaun Himalaya Faults thrust systems Deformation Convergence crustal strain

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

crustal Structure Revealed by a Deep Seismic Sounding Profile of Baijing-Gaoming-Jinwan in the Pearl River Delta

引用

Journal of Ocean University of China 2018年第1期17卷 186-194页

作者： ZHANG Xiang YE Xiuwei LV Jinshui SUN Jinlong WANG Xiaona CAS Key Laboratory of Ocean Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China University of Chinese Academy of Sciences Beijing 100049China Guangdong Earthquake Agency China Earthquake AdministrationGuangzhou 510070China

The Pearl River Estuary area, located in the middle part of the southern China coastal seismic belt, has long been considered a potential source of strong earthquakes above magnitude 7.0. To scientifically assess the potential strong earthquake risk in this area, a three-dimensional artificial seismic sounding experiment, consisting of a receiving array and seabed seismograph, was performed to reveal the deep crustal structure in this region. We used artificial ship-borne air-gun excitation shots as sources, and fixed and mobile stations as receivers to record seismic data from May to August 2015. This paper presents results along a line from the western side of the Pearl River Estuary to the western side of the Baijing-Gaoming-Jinwan profile. A two-dimensional velocity structure was constructed using seismic travel-time tomography. The inversion results show that the Moho depth is 27 km in the coastal area and 30 km in the northwest of the Pearl River Estuary area, indicating that the crust thins from land to sea. Two structural discontinuities and multiple low-velocity anomalies appear in the crustal section. Inside both discontinuity zones, a low-velocity layer, with a minimum velocity of 6.05 km s^(-1), exists at a depth of about 15 km, and another, with a minimum velocity of 6.37 km s^(-1), exists at a depth of about 21.5 km between the middle and lower crust. These low velocities suggest that the discontinuities may consist of partly molten material. Earthquakes with magnitudes higher than 5.0 occurred in the low-velocity layer along the profile. The deep Kaiping-Enping fault, rooted in the crust, may be one of the most important channels for deep material upwelling and is related to tectonic movement since the Cretaceous in the Pearl River Delta tectonic rift basin.

关键词： Pearl River Estuary seismic sounding profile crustal structure Kaiping-Enping fault earthquake potential

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

crustal structure of seismic velocity in southern Tibet and east-westward escape of the crustal material——An example by wide-angle seismic profile from Peigu Tso to Pumoyong Tso

引用

Science China Earth Sciences 2004年第6期47卷 500-506页

作者： S. Klemperer Department of Geophysics Stanford University Stanford CA94305-2215 USA

The reflecting events from Moho and other interfaces within the crust are recog-nized from the wavefield characteristics of P- and S-wave for the 480km long wide-angle seismic profile between Peigu Tso and Pumoyong Tso. Then, seismic crustal structures of P- and S-wave velocities and Poisson ratio under the nearly east-west profile in southern Tibet are interpreted by fitting the observed traveltimes with the calculated ones by forward modelling. Our interpreting results demonstrate that the crustal thickness varies remarkably in the east-west direction, showing a pattern that the crust could be divided into three parts bounded by the west of Dingri and the east of Dinggy? respectively, where the depth of Moho is about 71km for the western part, about 76km for the middle and about 74km for the eastern. There is one lower velocity layer (LVL) at the bottom of the upper crust with depth of 20—30 km. One of the distinct features is that the thickness of LVL abruptly thins from 24km on the west to 6km on the east. The other is that the velocity variation in the crust along east-west direction for both P- and S-wave displays a feature as quasi-periodic variation. The lower velocity (compared to the average value for the continent of the globe) in the lower crust and three sets of north-southward active normal faults are probably attributed to the coupling process of material delamination in the lower crust, crustal thicking and east-westward escape of the crustal material accompanied with the continental col-lision between India and Eurasia Plate.

关键词： southern Tibet, crustal structure, lower velocity layer,delamination, east-west escape.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Model of the crustal Magnetic Field in the Martian Aurora Zone

引用

Chinese Physics Letters 2011年第11期28卷 286-288页

作者： TONG Dong-Sheng CHEN Chu-Xin School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026

It is well known that aurorae are prominent on planets with a global magnetic field and occur where open magnetic field lines *** UV spectrometer used for investigating the characteristics of the atmosphere of Mars(SPICAM)on board the Mars Express made the first observation of auroral-type emission in the cusp region of the strong crustal magnetic field on Mars and found that the arc of the Martian aurora zone is very narrow in width,which obviously differs from that of other *** on the observation,we put forward a model of a crustal magnetic field on the Martian aurora zone through the morphology of Martian *** the model,equivalent currents are proposed;the topology and magnitude of the magnetic field generated by these equivalent currents are consistent with that of the crustal magnetic field in the Martian aurora *** morphology of the Martian aurora zone generated through the model matches well with the observations made by the Mars Express orbiter.

关键词： zone crustal currents

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

crustal motion of Chinese mainland monitored by GPS

引用

Science China Earth Sciences 2000年第4期43卷 394-400页

作者：朱文耀王小亚程宗颐熊永清张强叶叔华马宗晋陈俊勇许厚泽魏子卿赖锡安刘经南金标仁任金卫王琪 Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Institute of Geology State Seismological Bureau Beijing 100029 China National Bureau of Surveying and Mapping Beijing 100830 China Wuhan Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China Xi'an Institute of Surveying and Mapping Xi'an 710054 China Institute of Seismology State Seismological Bureau Wuhan 430071 China Wuhan Technical University of Surveying ang Mapping Wuhan 430070 China

: To measure and monitor the crustal motion in China, a GPS network has been established with an average side length of 1 000 km and with more than 20 points on the margins of each major tectonic block and fault zone in China. Three campaigns were carried out in 1992,1994 and 1996, respectively by this network. Here we present, for the first time, the horizontal displacement rates of 22 GPS monitoring stations distributed over the whole China and global IGS stations surrounding China, based on these GPS repeated measurements. From these results by GPS, we have obtained the sketch of crustal motion in China.

关键词： crustal motion in China GPS monitoring.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Zircon U-Pb-Hf constraints from Gongga Shan granites on young crustal melting in eastern Tibet

引用

Geoscience Frontiers 2019年第3期10卷 885-894页

作者： Nick M.W.Roberts Michael P.Searle NERC Isotope Geosciences Laboratory British Geological Survey Environment Science Centre Department of Earth Sciences University of Oxford

The Gongga Shan batholith is a complex granitoid batholith on the eastern margin of the Tibetan Plateau with a long history of magmatism spanning from the Triassic to the Pliocene. Late Miocene-Pliocene units are the youngest exposed crustal melts within the entire Asian plate of the Tibetan ***, we present in-situ zircon Hf isotope constraints on their magmatic source, to aid the understanding of how these young melts were formed and how they were exhumed to the surface. Hf isotope signatures of Eocene to Pliocene zircon rims(ε_(Hf)(t)=-4 to +4), interpreted to have grown during localised crustal melting, are indicative of melting of a Neoproterozoic source region, equivalent to the nearby exposed Kangding Complex. Therefore, we suggest that Neoproterozoic crust underlies this region of the Songpan-Ganze terrane, and sourced the intrusive granites that form the Gongga Shan batholith. Localised young melting of Neoproterozoic lower or middle crust requires localised melt-fertile lithologies. We suggest that such melts may be equivalent to seismic and magnetotelluric low-velocity and high-conductivity zones or "bright spots" imaged across much of the Tibetan Plateau. The lack of widespread exposed melts this age is due either to the lack of melt-fertile rocks in the middle crust, the very low erosion level of the Tibetan plateau, or to a lack of mechanism for exhuming such melts. For Gongga Shan, where some melting is younger than nearby thermochronological ages of low temperature cooling, the exact process and timing of exhumation remains enigmatic, but their location away from the Xianshuihe fault precludes the fault acting as a conduit for the young melts. We suggest that underthrusting of dry granulites of the lower Indian crust(Archaean shield) this far northeast is a plausible mechanism to explain the uplift and exhumation of the eastern Tibetan Plateau.

关键词： Tibet Himalaya Hf isotopes Zircon crustal melting

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：